A dead rat's forearm is regrown in a lab and successfully transplanted onto a living rat.

Dr. Frankenstein wishes he were this good:
In June, Massachusetts General Hospital
researchers announced they’d built the first
functioning lab-grown limb. The team amputated a dead rat’s forearm and chemically stripped
away living cells, leaving behind what’s called
the extracellular matrix, a kind of scaffolding for
everything from blood vessels to nerve networks.
The limb then spent two weeks growing muscular
and vascular cells in a custom-built bioreactor.
Electrical stimulation showed the resulting limb had
a grip strength 80 percent that of a newborn rat’s.
After being transplanted onto a living rat, the limb
circulated blood through its new vessels.

[This article originally appeared in print as "It's Alive! Well, Sort of."]